1. Field of the Invention
The present invention relates to indexing tables. More particularly, the present invention relates to an indexing table which includes an air-driven clamping mechanism. Even more particularly the present invention discloses an indexing table which includes sequentially configured means for lifting a tabletop, rotationally locating the tabletop, and locking the tabletop in a fixed position.
2. Prior Art
The need for a highly durable indexing table is well illustrated by the common requirement in machine shops of supporting a work-piece at a predetermined angle for performing operations thereupon.
Indexing tables are tables that may be rotated about an axis. In this way, a work-piece, such as an engine block, which is to be machined, may be precisely rotated to accurately position the piece. The use of an indexing table simplifies the process in that the work-piece does not have to be lifted off the table top, rotated, and set back down, especially as some pieces tend to weigh hundreds and even thousands of pounds. Additionally, indexing tables provide an extremely accurate and precise means for rotating and positioning a work-piece to be machined.
Currently produced indexing tables provide a work-piece mounting plate which includes an x-y grid pattern of threaded holes and precision bores. A work-piece is generally set atop the mounting plate and secured thereto via clamps, or the like. The mounting plate is then rotated until the desired rotational position of the piece is achieved.
To facilitate its rotation, the mounting plate is generally lifted by a cushion of air provided by an air compressor. The mounting plate is attached to a base via a pivot pin, or a mounting pin. The air pressure is generally supplied through the base consequently pushing the mounting plate upward. In this configuration, the mounting plate may be rotated about the axis of the pivot pin. It is to be appreciated that many times this pivot pin is damaged or broken because a work-piece on the mounting plate falls over while the mounting plate is being rotated. When this occurs, the indexing table must be disassembled and repaired.
Once the mounting plate appears to be in the appropriate rotational location, an operator then engages the locating mechanism of the indexing table. Currently produced indexing tables include a locating mechanism which is essentially a pivot pin or dowel that slides into an aperture at the bottom of the mounting plate. Because only one pivot pin is used to locate the mounting plate, the accuracy and precision of the locating mechanism is quite limited. A source of pneumatic pressure, such as a compressor, is used to push the pivot pin into the aperture where it is held. Additionally, it is to be appreciated that currently produced indexing tables use the pivot pin or dowel to locate the mounting plate only at 90.degree. intervals. Positioning the mounting plate at other angular intervals currently requires manual location of the mounting plate.
Once the mounting plate has been located, it is then locked into place by the use of a manually operated clamp. Occasionally, an operator will forget to lock the mounting plate into place by tightening the clamp. If this occurs, both the locating pin and the mounting pin may be bent or broken. If the mounting plate is rotated, the locating pin will be bent or broken. If the mounting plate is moved laterally, both the mounting pin and the locating pin will be bent. It is well known in the art that these pins are often bent while a work-piece is being machined upon the mounting plate, rendering the indexing table useless until the pin(s) have been replaced. This can be a time consuming as well as expensive task that requires disassembling the table and repairing it.
Even if the mounting plate is locked down manually, as is the case with currently produced indexing tables, the risk still exists that the support plate may be moved if a work-piece it is supporting falls over, etc. Once again, both the mounting pin and the locating pin may be damaged or destroyed.
Additionally, it is to be appreciated that currently produced indexing tables include several handles, wherein each handle is used for a different purpose. Essentially, one handle is provided to activate the means for lifting the mounting plate and one handle is provided to activate the means for locating the mounting plate at one of the four 90.degree. angle positions. A separate handle is used to manually clamp the mounting plate down to reduce the chance that the mounting plate will be accidentally moved due to any machining or slippage of a work-piece.
Because several different handles are utilized in the operation of currently produced indexing tables, it is well known in the art that operators, from time to time, tend to push the wrong handle. Therefore, if the handle to lift the table top is activated and the table is also locked down, damage can occur to the table itself.
Thus, it is to be appreciated that what is needed is an indexing table that is simpler and safer to operate. Additionally, what is needed is an indexing table that will not break if the table top is shifted because of some machining process taking place thereupon.
It is to the solution of the above presented problems to which the present invention is directed.